There is conventionally disclosed an electrochemical machining method that forms a bent hole in a workpiece formed of a metal material by adjusting an exposed area of an electrode provided at a tip end of a flexible member (see Patent Document 1). Further, there is disclosed an electrochemical machining method that forms a bent hole by changing a way of applying a potential to two or more electrically-independent electrodes provided at a tip end (see Patent Document 2). Furthermore, there is disclosed an electrochemical machining method that uses a hollow bent insulation-coated electrode to form a bent hole (see Patent Document 3).